Preparation and characterization of carboxylic-functionalized multi-walled carbon nanotubes

L. K. Zakiyah, M. M. Gui, R. S. Foo, A. R. Mohamed, S. P. Chai

    Research output: Contribution to journalArticleResearchpeer-review


    The functionalization of pristine CNTs is necessary for carbon nanotubes (CNTs) to be fully utilized, with the aim of increasing the nanotube reactivity and solubility in aqueous solutions. In this study, multi-walled carbon nanotubes (MWCNTs) were functionalized with a carboxylic group as this was an important step prior to application. The carboxylic group-functionalization was conducted through acid treatment, using sulphuric and nitric acids mixed at a ratio of 3:1 (v/v) and sonication for 30 min under different temperatures and time durations. The functionalization conditions of 50°C × 5 h and 60°C × 3 h were identified to be most suitable for introducing a carboxylic group onto the nanotube surfaces. The percentage of total weight loss due to the carboxylic group on the MWCNTs treated at 50°C × 5 h and 60°C × 3 h obtained from the thermogravimetric analysis was 13.26% and 13.76%, respectively. For both samples, peaks corresponding to the carboxylic group were identified in the FT-IR spectra. The changes in the morphology of the treated MWCNTs were also observed under SEM analysis.

    Original languageEnglish
    Pages (from-to)91-100
    Number of pages10
    JournalASM Science Journal
    Issue number2
    Publication statusPublished - 2011


    • Acid treatment
    • Carbon nanotubes
    • Carboxylic groups
    • FTIR
    • Functionalization
    • Oxidation
    • Scanning electron microscopy
    • Sonication
    • TGA

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